At present, the interoperation between subsequent evolution network of Code Division Multiple Access (referred to as CDMA) network and Long Term Evolution (referred to as LTE) network is a trend in network development. However, it will be a complex substitution process for the evolvement from the commercial CDMA network to the LTE network, and in the substitution process, there will be long-period coexistence of the two networks, during which the two kinds of wireless networks will be interconnected.
Regarding handover of an access terminal from the LTE system to the HRPD system (i.e. LTE-HRPD interoperation), when the access terminal is handed over from the LTE system to the HRPD system, considering delaying sensitive services (e.g. VoIP service for voice transmission on IP network), the access terminal needs to pre-register HRPD through the LTE system, and establish HRPD session and IP session.
At present, in order to reduce modifications of the existing Legacy HRPD protocol stack as much as possible, and shield the impact on the different specific wireless access techniques brought by high-level protocol, in the LTE-HRPD interoperation specifications, a virtual connection is defined for the transmission of data and messages. Moreover, in the connection layer specification of the LTE-HRPD interoperation specifications, Signaling Adaptation Protocol is defined for air connection management under a tunnel mode, i.e, establishment and release of virtual connection are performed through the Signaling Adaptation Protocol.
At present, during the active handover from the LTE system to the HRPD system, the access terminal sends a HRPD air interface connection establishment request to the access network, at this time, if is a virtual connection exists or a virtual connection is being established, as for the access network, there already exists a link connection, therefore the access network will not accept the connection establishment request, and will refuse the HRPD air interface connection establishment request from the access terminal, and this will lead to a failure in active handover; and as for the access terminal, since the wireless environment changes, the LTE signals are not sufficient to support the service transmission and the request of handover to the HRPD system is refused by the access network, in this case as there is no wireless coverage available, the service of the access terminal is made to be interrupted.
Thus, during the process of handover of an access terminal from the LTE system to the HRPD system, if a virtual connection has existed or a virtual connection is being established, the data processing of the access terminal and the access network will be made disordered, which will cause a long-time interruption in the service of the access terminal and affect processing efficiency of the access terminal and the access network, thereby affecting the processing efficiency of the whole system.